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Paralenorthis alata
Taxonomy
Spirifer alatus was named by de Sowerby and Murchison (1839) [Lectotype designated by Bates (1969).]. Its type specimen is GSM. 6868, a valve (Internal mould of brachial valve), and it is a 3D body fossil.
It was recombined as Orthis alata by Davidson (1869); it was recombined as Lenorthis alata by Bates (1969); it was recombined as Paralenorthis alata by Jaanusson and Bassett (1993) and Reyes-Abril et al. (2010).
It was recombined as Orthis alata by Davidson (1869); it was recombined as Lenorthis alata by Bates (1969); it was recombined as Paralenorthis alata by Jaanusson and Bassett (1993) and Reyes-Abril et al. (2010).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1839 | Spirifer alatus de Sowerby and Murchison p. 49 figs. pl. 22 f. 7 |
| 1868 | Orthis carausii Davidson p. 315 figs. pl. 16, fig. 23. |
| 1869 | Orthis alata Davidson p. 232 figs. pl. 33, figs. 17-21 |
| 1969 | Lenorthis alata Bates pp. 10 - 14 figs. PI. 2, fig. 14; PL 3, figs. 1-7; PI. 4, figs. 1-10; PL 5, figs. 1-6 |
| 1993 | Paralenorthis alata Jaanusson and Bassett p. 34 |
| 2010 | Paralenorthis alata Reyes-Abril et al. pp. 294 - 296 fig. 6 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Paralenorthis alata de Sowerby and Murchison 1839
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Invalid names: Lenorthis carausii Davidson 1868 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| D. E. B. Bates 1969 | Sub-semicircular ventro-biconvex Lenorthis two-thirds as long as wide (in large specimens), approximately one quarter as deep as wide, the pedicle valve being at least twice as deep as the brachial valve ; widest at the hinge line, with alate cardinal angles becoming less accentuated with growth, anterior margin not indented; anterior commisure slightly sulcate; delthyrium and notothyrium open; pedicle valve convex but with concave or flattened portions adjacent to the cardinal angles, interarea slightly concave, apsacline, about one-sixth the length of the valve; brachial valve gently convex with a shallow median sulcus and concave flanks to the folds becoming flat towards the cardinal angles, interarea anacline, curved and half the length of the ventral one ; ornament on both valves of approximately 40 rounded costae and equal rounded interspaces, strong in the median portion of the valves but becoming fine and crowded towards the hinge lines, with a wavelength of 07 mm. at 5 mm. from the dorsal umbo, the pedicle valve bearing a median costa and the brachial valve 4 costae in the sulcus; fine parvicostellae and growth lines present; ventral interior with blunt pyramidal teeth, the posterior faces parallel to the interarea and apparently bearing a central ridge aligned parallel to the edge of the delthyrium: dental lamellae vertical, receding; muscle scars approximately twice as long as the delthyrium and extending one-third the length and one-fifth the width of the pedicle valve, approximately pentagonal in outline with the adductor tracks extending linearly forward and not enclosed by the diductor tracks, the latter extending slightly further forwards than the adductor tracks and with their anterior margins running obiliquely forwards from the dental lamellae making an angle of about 50 with the hinge line; grooves present in the sides of the dental lamellae between the diductor tracks and the margin of the delthyrium ; vascula media extend from the anterior ends of the diductor tracks and diverge at the same angle; margin of valve deeply crenulate; dorsal interior with socket ridges diverging at just under 90 from each other, short, blade-like on their postero-ventral edges, rounded at their ends, bearing faint curved striae on their outer faces; sockets excavated below the hinge line, split by a subdued median ridge whose growth forms a ridge in the interarea, outside the socket ridge, aligned on the umbo; cardinal process a simple ridge, thickened on its antero-ventral edge, flanked by low accessory ridges; notothyrial platform extending into a thick rounded median septum running forwards for just under half the length of the valve ; posterior adductor scars quadrangular, over twice as wide as long, anterior adductor scars half the width but over twice as long as the posterior adductor scars; mantle canal system digitate, vascula media diverge from the anterior adductor scars, vascula myaria and traces of vascula genitalia present; margin of valve deeply crenulate. | |
| J. Reyes-Abril et al. 2010 | Paralenorthis with mucronate outline, acute cardinal angles, allometric growth, lowest values of length relative to width corresponding to largest valves, and sulcate anterior commissure; dorsal interarea steeply anacline to catacline; ornamentation costate with up to 38 ribs, of which some subcentral ribs have slightly delayed origin; ventral muscle field of subrhomboidal outline. |